Underactive Bladder: A New Entity in Voiding Dysfunction?

Overactive bladder (OAB) is a very common urologic entity and complaint among urologic patients.  OAB represents a constellation of symptoms including urgency, with or without incontinence, frequency and nocturia.[1]  See our prior blog entry on Female Incontinence for more details on OAB.  There are a number of causes of OAB and subsequently OAB can be related to a variety of coincident urologic diagnoses like bladder outlet obstruction in men, pelvic organ prolapse in women, neurologic or systemic diseases like diabetes.  In addition, OAB has a number of excellent treatments progressing from behavioral therapy (i.e. modifying fluid intake) to medications, and finally surgical devices (like Interstim or Tibial Nerve Stimulation).

Underactive bladder (UAB) is similar to OAB in that it represents a constellation of symptoms and has a number of etiologies and coincident urologic diagnoses.  Symptoms of UAB are strangely similar to OAB and can include:

• urgency
• frequency
• nocturia
• hesitancy
• straining to void
• sensation of incompete voiding
• urinary retention
• incontinence (overflow or urgency)

UAB may occur without symptoms or associated diseases.  However, some associated diseases and causes of UAB (are once again similar to OAB and) include:

• neurologic disease
• muscle disease or failure (includes the detrusor (bladder) muscle or muscles of the pelvic floor)
• age-related
• medication-related
• bladder outlet obstruction (most commonly benign prostatic hyperplasia in men) [2,3]

Unlike OAB, there are no good treatments for UAB.  Therefore UAB remains an underappreciated entity and therefore is lacking in understanding and concensus regarding its diagnosis and treatment.  Previous attempts at classifying UAB used the terminology detrusor underactivity (DU) to indicate an inability of the detrusor (or bladder) muscle to contract with enough force to expel urine.  Recent studies indicate the UAB is more common than previously predicted.

• In a study of 1,179 men and women older than 65 years-old with non-neurogenic voiding dysfunction and lower urinary tract symptoms (LUTS) [4]
• 40% of men and 13.3% of women had DU (similar to UAB)
• the proportion of patients with DU increased with age
• A study of 181 elderly patients with LUTS identified DU in 48% of men and 12% of women. [5]
• 40% of men in this study had bladder outlet obstruction (BOO), only 10% of men with DU had BOO

UAB can notably cause long-term, chronic issues including urinary retention requiring catheterization, urinary incontinence and/or recurrent urinary tract infections.  

Therefore the First International CURE-UAB (Congress of Urologic Research and Education on UnderActive Bladder) was held in Washington, DC in February 2014 in the hopes of addressing some of the shortcomings in the uderstanding of UAB.  The CURE-UAB was founded and led by David Chancellor, BS, Vikas Tyagi, MD and Michelle Gruber, BS.  Over 100 health care experts met at the congress to discuss, define and outline research goals for the future of UAB.  The meeting and subsequent research is funded by the NIH (National Institutes of Health).  To find out more about UAB, visit the website: http://www.underactivebladder.org/

[1] Chapple CR, Artibani W, Cardozo LD, et al. The role of urinary urgency and its measurement in the overactive bladder symptom syndrome: current concepts and future prospects. BJU Int 2005;95:335–40.
[2] van Koeveringe GA, Vahabi B, Andersson KE et al: Detrusor underactivity: a plea for new approaches to a common bladder dysfunction.  Neurourol Urodyn 2011; 30: 723.
[3] Osman NI, Chapple CR, Abrams P et al: Detrusor underactivity and the underactive bladder: a new clinical entity? A review of current terminology, definitions, epidemiology, aetiology, and diagnosis. Eur Urol 2014; 65: 389.
[4] Jeong SJ, Kim HJ, Lee YJ et al: Prevalence and clinical features of detrusor underactivity among elderly with lower urinary tract symptoms: a comparison between men and women. Korean J Urol 2012; 53: 342.
[5] Abarbanel J and Marcus EL: Impaired detrusor contractility in community-dwelling elderly presenting with lower urinary tract symptoms. Urology 2007; 69: 436.